Mineral concentrating and separating apparatus



March 28, 1961 N. H. A. RODMAN ETAL 2,976,994

MINERAL CONCENTRATING AND SEPARATING APPARATUS Filed Feb. 6. 1958 3 Sheets-Sheet 1 FIG. 1

Mm. ATTORNE 1 d EZ'VENTORS M M March 28, 1961 N. H. A. RODMAN EIAL 2,976,994

MINERAL CONCENTRATING AND SEPARATING APPARATUS Filed Feb. 6, 1958 3 Sheets-Sheet 2 FIGS 1 ENToRg 2 m 4 M BYQ W ATTORNEY March 28, 1961 N. H. A. RODMAN ETAL 2,976,994

MINERAL CONCENTRATING AND SEPARATING APPARATUS ATTO EY Unite MINERAL CONCENTRATING AND SEPARATING APPARATU Filed Feb. 6, 1958, Ser. No. 713,641

6 Claims. (Cl. 209-211) This invention relates to concentrating apparatus, such as for concentrating minerals, and, more particularly, to a novel multi-stage centrifugal concentrator having improved efficiency of separation of concentrates from tailings.

A known form of mineral separating and concentrating apparatus of high efiiciency comprises a concentrating chamber of generally circular cross-section having a tailings discharge outlet in the top thereof and a concentrating discharge outlet in the bottom thereof, axially aligned with one another, an injector for discharging .mineral containing sludge into the chamber, an air inlet tube disposed in the concentrate discharge outlet and extending into the chamber, a concentrate separating head disposed above the concentrate discharge outlet and surrounding t-he air inlet tube, the head being spaced from the bottom of said chamber to form a passage therebetween leading to the concentrate discharge outlet, the separating head being formed with a splitting edge adjacent the passage for separating the concentrate from the sludge as the former moves into the passage. In

addition, the apparatus embodies an ejector having aspirally disposed passage for introducing the mineral containing sludge into the chamber in a substantially circular path within the chamber wherein an initial part of the passage spirals around the chamber'in a horizontal plane, a second part thereof circles downwardly at an' incline, and a third and final portion spirals in a horizontal plane within the chamber, the passage gradually opening into the chamber at a point intermediate its extent, from zero opening to full extent at the terminal end of the passage, and in gradually decreasing depth to zero depth in the final portion of its extent whereby to maintain the heavier mineral content in the passage over a substantial portion of its travel therein while discharging lighter foreign material continuously from its point of opening to its point of termination, the heavier mineral concentrate being caused to discharge from the passage in its portion of final extent as its depth decreases and at a level below the first point of entry of the sludge to said chamber.

While the apparatus has a high efficiency of separation of the concentrate from the tailings, a substantial increase in such efficiency is possible by utilizing the underlying principles of such apparatus in a multi-stage unit in accordance with the present invention. Thus, the concentrating apparatus according to the present invention comprises a stack including a plurality of such known concentrators arranged in cooperating relation in a novel manner.

More specifically, the apparatus of the present invention includes a stack of at least three such concentrators, one or more of which may be modified as to relative direction or orientation of the feed input, and one of which is utilized as a middlings outlet or separator. The uppermost stage concentrator is used to introduce water under The next lower stage concentrator States Patent 2,976,994 Patented Mar. 28, 1961 ice spects the rotation direction of the spiral path. Also, the

spiral path moves upwardly through the concentrator. As the rotary direction of middlings outflow is, of necessity, reversed as to the rotary direction of Water in flow, it is in the same rotary direction as the feed injection.

While the vortex and cone splitter actions of the known concentrator unit are present in the invention apparatus, the major part of the concentration is effected by centrifugal action. The feed injected through the feed injection stage under pressure moves circumferentially around this stage for a turn and a quarter and their moves along the upwardly spiralling inwardly opening passage whose gradually widening inner Wall opening gradually merges into the fiat inner surface of the unit. As the feed leaves the fiat of the feed injection spiral it enters the fiat of the upwardly extending middlings exit spiral whose inner opening gradually closes until the separated middlings and some concentrate move circumferentially for a turn and a quater in a closed passage, after which the middlings and the some concentrate are-tangentially discharged.

During this movement, the middlings and concentrate are separated from the lighter tailings by centrifugal force versus the action of gravity. There is no vortex or turbulence separation action from the injection stage to the exit stage. Whatever fines are not carried out through the. exit stage remain in suspension in the bowl of the apparatus.

More specifically, the centrifugal spray of water from the uppermost stage creates a turbulence in the center of the bowl while simultaneously washing the light tailings from the side walls of the feed injection and middlings exit stages. Also, this spray has a cleansing action on the heavier middlings and concentrate moving upwardly along the inwardly open portions of the injection and exit stages between the closed circumferential passages of these two stages.

Furthermore, the turbulence is present as in the known single stage unit so that fines from the feed injection stage, plus fines separated from the walls of the injection and exit stages and those rubbed oif the middlings and concentrate subjected to the vortex action While moving upwardly through the inwardly open portions of the injection and exit stages, and moving into the vortex above the splitter are moved upwardly to the fines exit or discharge.

The splitter at the bottom of the apparatus effects some separation but no longer is required to do the major part of the separation as the major separation is effected by centrifugal action which is essentially a separation based on weights or densities.

The pressure used in injecting the feed is such that, coupled with the centrifugal force, the effect is that there is very little dropping of concentrate toward the splitter oulet due to gravity. Such concentrate as may drop is further scrubbed of fines by the turbulence or vortex action and the heavier particles move outwardly toward the surfaces of the injection and exit stages for discharge from the exit stage.

In a preferred embodiment of the invention, a second water injection stage is provided beneath the feed injection stage to provide a spiralling spray of water under pressure to further wash fines from any concentrate settling toward the splitter outlet. The splitter functions in i the previously known manner to further separate heavies or concentrate from fines, and the thus separated heavies may be re-circulated with additional injected feed. Such recirculation is generally necessary only with very low grade feed. If the metallurgy so indicates, this splitterseparated concentrate can be screened for it rther concentration.

For an understanding of the invention principles, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings. In the drawings:

Fig. 1 is an axial sectional view of one form of concentrator embodying the invention;

Fig. 2 is an outside elevation view thereof;

Fig. 3 is a diametric sectional view of one of the structurally identical stages;

Fig. 4 is an axial sectional view of a preferred form of concentrator; and

Fig. 5 is an outside elevation view thereof.

Referring to Figs. 1, 2 and 3, a concentrator embodying the principles of the invention is illustrated as comprising three structurally identical centrifugal stages or units A, 10B and NC, a light tailings or fines discharge assembly 20, and a vortex bowl 30. Assembly 20 engages upper stage 10A and bowl 35 engages lower stage lilC, the light tailings discharge assembly, centrifugal units, and bowl being suitably secured together by bolts or the like with the interposition of suitable sealing gaskets.

Each unit iii comprises a base 11 and a head 12 which mate with each other and conjointly form a generally spiral tubular passage which is disposed outside the inner periphery 13 of the unit and spirals inwardly to open in progressively increasing degree on the inner surface of the unit. Passage 15 makes two complete turns around the unit, first making approximately one and onequarter turns horizontally around the unit, then continuing for one-half turn in a downwardly inclined direction, as at 16 (in the normal orientation of a unit 10), and terminating in a substantially one-half turn in a horizontal plane, as at 17.

At a point before portion 16, indicated at 14 in Fig. 3, the passage 15 gradually opens into the interior of the unit, the opening increasing in width from zero to the full diameter of passage 15, and the passage 15 correspondingly decreasing in depth from its full diameter to onehalf its diameter where section 16 begins. inclined section 16 is of constant depth and width but, in terminal section 17, the passage gradually decreases in depth from one-half its initial diameter to zero where it merges as a flat with inner periphery 13.

Fines or light tailings discharge assembly 2% includes a substantially conical base 21 bolted or clamped to head 12 of top unit ltlA, a vortex tube 25 extending axially downwardly from base 21 through the units 19 to just above bowl 3%, an axial discharge 22 extending upwardly from tube 25, and a side outlet tube 23. A pressure regulating and relief tube 24 is secured in axial alignment with dis charge section 22.

Bowl 39 has a concentrate discharge opening 31 through which extends axially a central air inlet tube 32 axially adjustably mounted in a spider 33 secured to bowl 30. Tube 32 is axially aligned with tube 25 and carries on its upper end a preferably conical concentrate splitter head 35. 7

Upper unit WA is positioned with normal orientation and has its inlet MA to its passage 15 so disposed that the spiral direction is counterclockwise as viewed from the top. Inlet 18A is connected to a source of water at a predetermined pressure.

Concentrate and middlings exit unit MB is positioned with the same orientation as unit 10A. However, as this is a discharge unit, the flow along passage 15 is in a clock- 2,976,99 i, m r v ,4 wise direction (as viewed fromthe top) toward outlet 183.

The bottom unit 10C, which is the feed injecting unit, is reversely oriented, or inverted, relative to units 10A and 10B, so that feed under pressure entering its inlet 18C flows in a clockwise direction (as viewed from the top) through its passage 15 and thence in the same direction into and through the passage 15 of unit 10B. Due to inversion of unit 10C, its inclined section 16 spirals upwardly. Units 10B and are so positioned that the flats at the terminal ends of their passage sections 17 are aligned for continuous flow of the feed from inlet 10C to unit 103.

In the described arrangement, the separation of concentrate and middlings from the tailings occurs principally by centrifugal force in the manner set forth above. The splitter cone 35 is axially adjustable to set the level at which it skins oif tailings from that part of the concentrate moving toward outlet opening 31. An outstanding advantage of the multi-stage apparatus, as compared to the known single stage unit, is that the additional height makes it possible to obtain more efiicient settling of the heavies and provides for increased capacities and production.

With a feed of 30-45% Fe and 25% Si to feed injector inlet 18C, the middlings and the part of the concentric at outlet 18B is 10 to 45 mesh with 56% Fe and 18% Si.

The described embodiment of the invention acts as follows: With mixed feed introduced at 18C, and with water under pressure introduced at 18A, the feed moving upwardly and the water moving downwardly result in washing of fines or tailings from the feed so that a concentrated feed, comprising middlings and concentrate, is discharged from the exit 183. Some of the heavier concentrate falls, by gravity, downwardly into the bowl 3t), and the fines or tailings are washed down by the water and circulate through the vortex tube 25 in which an upward flow of air is provided due to the whirling action or cyclonic action of the water in the apparatus. Those heavier particles, which fall into the bowl 30, pass out through the opening 31 and may be recirculated with the incoming feed. The cone 35 splits tailings from these heavier particles and the split tailings are drawn upwardly through the vortex tube 25.

The principal outletfor the concentrated product is the discharge 18B, from which is discharged middlings and a major portion of the concentrate. However, some of the heaviest concentrate falls by gravity, into the bowl 30 and passes out through the outlet 35. All of the very light tailings, or fines, however, pass out through the exit 23.

In the preferred embodiment of Figs. 4 and 5, an additional unit 10D is interposed between feed injector unit 10C and bowl 30. Unit 10D is oriented in the same direction as upper units 10A and MB. A source of water at a predetermined pressure is connected to its inlet 18D so that water flows in a counterclockwise direction around its passage 15 (as viewed from the top) and is discharged into the interior as a downwardly spiralling spray. This spray further washes fines from the concentrate for upward movement in vortex tube 25, increasing the efficiency of separation, and also the height of the unit with its attendant advantages.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise Without departing from such principles.

What is claimed is:

1. Mineral concentrating and separating apparatus comprising, in combination, a plurality of structurally identical annular units superposed in coaxial relation to define a substantially cylindrical upright concentrating chamber; tailings discharge means closing the upper end of said chamber; concentrate discharge means at the lower end of said chamber; means providing an air flow through the bottom of said chamber upwardly toward said tailings discharge means; each of said units having a separate spirally disposed passage therein having a tangentially extending outer end; an initial part of said passage spiralling around the unit exteriorly of its inner surface in a substantially diametric plane of the unit for at least 360 degrees, an intermediate and continuing part of said passage circling axially at an incline along the inner periphery of the unit, a terminal and continuing part of said passage spiralling along the inner periphery of the unit in a substantially diametric plane of the unit; said passage, at a point intermediate the ends of said intermediate part, gradually opening through the inner periphery of the unit from zero opening to full extent at the inner terminal end of said passage, and gradually decreasing in depth to zero at the inner terminal end of said passage to form a flat; the topmost unit having an orientation such that the intermediate part of its said passage spirals downwardly within the chamber; said topmost unit being constructed and arranged to have a supply of water at a predetermined pressure connected to its tangentially extending outer end; the intermediate unit immediately beneath the topmost unit having the same orientation as the topmost unit so that the intermediate part of its said passage spirals downwardly within the chamber; the lower unit immediately beneath said intermediate unit having an orientation reversed with respect to the orientation of said topmost and intermediate units so that the intermediate part of its said passage spirals upwardly within the chamber; the flats of the intermediate and lower unit being aligned; the lower unit being constructed and arranged to have a supply of unclassified feed at a predetermined pressure connected to its tangentially extending outer end; the unclassified feed passing along the passage of the lower unit with separation of concentrate from tailings by centrifugal force, with tailings being carried by the air flow to the tailings discharge and the concentrate moving along the outer wall of the passage of the lower unit, upwardly of said chamber, and then along the outer wall of the passage of the intermediate unit with further separation of concentrate and tailings by centrifugal force; the spiral spray of water from the topmost unit washing tailings from the concentrate passing along the inwardly open parts of the passages of the lower and intermediate unit.

2. Apparatus as claimed in claim 1 including a fourth unit disposed beneath said lower unit and having the same orientation as the topmost and intermediate units so that the intermediate part of its said passage spirals downwardly within the chamber; said fourth unit being constructed and arranged to have a supply of water at a predetermined pressure connected to its tangentially extending outer end; the spiral spray of water from the fourth unit washing tailings from any concentrate moving toward said concentrate discharge means.

3. Apparatus as claimed in claim 1 in which said concentrate discharge means comprises a bowl having an axial outlet; and a splitter cone in said bowl adjustable axially of said outlet; said air flow providing means directing air inwardly through said axial outlet for deflection by said cone; said cone stripping fines from concentrate moving toward said axial outlet.

4. Apparatus as claimed in claim 3 in which said tailings discharge means includes a vortex tube extending axially downwardly of said chamber from the upper end thereof to a point spaced a relatively short distance above said cone.

5. Apparatus as claimed in claim 2 in which said concentrate discharge means comprises a bowl having an axial outlet; and a splitter cone in said bowl adjustable axially of said outlet; said air flow providing means directing air inwardly through said axial outlet for deflection of said cone; said cone stripping tailings from any concentrate moving toward said axial outlet.

6. Apparatus as claimed in claim 5 in which said tailings discharge means includes a vortex tube extending axially of said chamber from the upper end thereof to a point spaced a relatively short distance above said cone.

References Cited in the file of this patent UNITED STATES PATENTS 2,008,643 Lockett July 16, 1935 2,768,745 Albertson Oct. 30, 1956 2,783,887 Chisholm Mar. 5, 1957 2,909,283 Duesling Oct. 20, 1959 

